In case it wasn't clear that he was out of Metal Gear, he responded to the question "did they even ask you to do it?" with "nope." So there you go: as far as we know, Hayter will not be a part of Metal Gear Solid V.

Now, look. I've been playing the Metal Gear series since the NES. I remember how iconic Hayter sounded during the first few moments of Metal Gear Solid -- he will always be a part of the franchise, and it will sound incredibly weird without him. But still, he is just one part of the series, which has a lot more to offer than just one role.

Of course, this could all be a ruse, and as I joked in the comments for the reveal, he could still show up at some point.